The goal of this project is to analyze cerebrospinal fluid macrophages from pediatric patients with abnormal neuropsychological findings for clonally integrated human immunodeficiency virus. Preliminary data from HIV-infected adult patients with dementia demonstrate that HIV is clonally integrated in cells recovered from CSF. In one case where the integration site has been sequenced, the virus is integrated in the region of PDGF-A. In other clinical settings where HIV has been found to be clonally integrated, the involved cell was identified as a macrophage. The etiology of chronic encephalitis or abnormal neuropsychological development in pediatric patients infected with HIV is currently unclear. Two distinct clinical entities exist with respect to neuropsychological deficits: 1) a progressive neuropsychological abnormality in infants and young children; 2) AIDS-dementia-like picture in adolescents similar to adults. Both groups of patients acquired their HIV infection perinatally, but the etiology of the two distinct neuropsychological entities is unclear. This project proposes to analyze CSF from pediatric patients with abnormal neuropsychological findings and compare the CSF to older pediatric patients with evidence of dementia. CSF analysis will focus on the presence of a clonally-integrated retrovirus. In those cases where HIV is found integrated, further sequencing of the integration site will help to identify if PDGF-A is also involved in pediatric patients with AIDS- dementia or abnormal neuropsychological findings; or to determine if the integration site is different. This information will help in the understanding of CNS disease in childhood AIDS and may offer new insight into the pathogenesis and treatment of this disease.